Astigmatism is a vision problem that occurs when the cornea or the lens in the eye is irregularly shaped. This prevents light from focusing properly on the retina, which leads to blurred vision at any distance. Slight astigmatism may be corrected using prescription glasses or contact lenses.
Myopia, or “nearsightedness”, is the most prevalent refractive vision problem in the U.S., with 41.6 percent of the population affected by the condition. Myopia occurs when the eyeball itself is too long, causing light rays to focus in front of the retina instead of on it. This makes it difficult for people to see things clearly from far away.
Hyperopia, on the other hand, afflicts roughly a quarter of the U.S. population. It is the exact opposite of myopia. People with hyperopia often have smaller eyeballs, which cause light to focus behind the retina.
Presbyopia often affects adults age 40 and above, making it the only age-related condition on the list. It is often described as extreme far-sightedness, as those with presbyopia often find it difficult to see things that are very near to them, such as the sentences in a book or thread used for sewing.